From MangaHelpers:

At the young age of 18, Erai Tenka is the president of a highly successful IT company and is filthy rich. He has everything he wants, except for one thing: a girlfriend. The truth is, he is desperately shy around women. He is attempting to get over his shyness by hanging out with a team of bunny-girls, but it hasn't seemed to help.

One night, Tenka goes out walking alone and is very nearly mugged. Luckily, a girl shows up and rescues him, and Tenka falls in love with her at first sight. It turns out that she's a student at his little sister Yuika's high school, so Tenka enrolls immediately. Unfortunately, his crush, Himuro Sai, thinks he's a creepy, perverted stalker, and he's too flustered around her to explain himself! He'll have to get over his shyness if he wants to have a chance to win Sai's heart! [tethysdust]